1. Heat oil in a non-stick pan. Add chicken in batches and cook over a medium heat until lightly browned. Place chicken in the removable crockery pot.
2. Top chicken with mushrooms, leeks, wine, stock, pepper, salt and lemon thyme. Cover with lid and cook on Low 8-10 hours or High 4-5 hours.
3. Stir in blended flour, cream and sour cream 1 hour before end of cooking. Replace lid and continue cooking.